The present invention is a lapidary device for use by amateurs and professionals to facilitate the grinding of a convex face on an elongated rounded cabachon to both a predetermined radius of longitudinal curvature and a predetermined shorter radius of transverse curvature. A cabachon or "cab" is a thin slice of rock which is temporarily mounted on the end of a cylindrical dowel known as a "dop stick" for shaping the cabachon by a grinding wheel. The specific function of the device is to facilitate manipulations for grinding a convex face on a cabachon of generally oval plan configuration.
Lapidary devices for grinding cabachons are disclosed in the Geizentanner U.S. Pat. No. 3,279,127, the Reed U.S. Pat. No. 3,844,070, and the Lindzy Pat. No. 3,849,945.
The Geizentanner patent discloses a power-actuated grinding apparatus for simultaneously grinding the faces of a plurality of round cabachons to spherical convex curvature. The apparatus is not capable of grinding a cabachon of oval plan configuration to produce a convex face of predetermined longitudinal and transverse curvature.
The device disclosed in the Reed patent is designed to grind a rounded peripheral edge on a cabachon and is capable of forming the cabachon to a predetermined oval plan configuration. No method is disclosed in the patent for forming the face of the cabachon and apparently the finished cabachon has a flat face.
The device disclosed in the Lindzy patent is capable of forming a cabachon with a convex face of the configuration of a fragment of a cylinder and also is capable of forming a convex face of spherical curvature. The device is not capable of forming an oval convex face of predetermined longitudinal and transverse curvature.